I think you’re right it think Solana is devaluing ETH because of this trade off and I have even thought about it myself but I don’t think that ETH is over or done for by any means. It’s so engrained in so much and I just don’t see it ever being completely abandoned. SOL though is emerging and for now might be a good play in the short term but long term I think I am more set on ETH
If comparing both network you would see that Sol is fast increasing in term of price than ETH but when talking about long term investment then we can choose Eth, though I am more passionate about Bitcoin but even though eth/sol seems to be more affordably as of now, from my view this market would mostly favor bitcoin the more than altcoin, even though lot of people has been saying that not yet for altcoin season i still believe they won't be that outperforming bitcoin.